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460
Democrtius
Democrtius ;s atom was the idea that matter is made of indivisible particles that are called atoms. Most of his ideas were rejected because he did not have the necessary equipment. -
John Dalton 1766-1844
John Dalton created Dalton's atomic theory .He composed many ideas such all elements are made of atoms,an atom of hydrogen and an atom of carbon are different,componds are made of 2 or more elements,and the ratio of atoms in HCI is https://www.youtube.com/watch?v=sDoH5fPTOfo -
J.J Thompson
J.J Thompson discovered the electron which has a negative charge. While working with a gas discharge tube he discovered cathode rays wich are made of electrons. In the tube he noticed that the electrons move from the negative end of the tube to the positive end because opposites attract. -
Lord Ernest Rutherford
Rutherford discovered the alpha particle with a positive charge. He made an experiment with gold foil. Most of the particles passed straight through the foil. When they hit the foil they scattered in many directions. He knew that the nucleus was positively charged because the particles were bouncing back rather than becoming stuck to the nucleus. -
Niels Bohr 1900
Bohr's model was called a planetary model because the electrons go around the nucleus like planets orbit the sun. He discovered that electrons in the same atom differ because of their location. In an atom the fourth energy level holds 32 electrons.The electrons need to absorb energy to jump from the second level to the third level. he knew that for an electron to fall it would lose energy.
